Epitaxial film growth and optoelectrical properties of layered semiconductors, LaMnXO (X=P, As, and Sb)

Thin films of LaMnXO (X=P, As, and Sb), which are isostructural compounds of the newly discovered superconductor, LaFeAsO, were grown epitaxially on MgO(001) substrates at similar to 680 degrees C by pulsed laser deposition. Postdeposition thermal annealing at 1000 degrees C in evacuated silica glass ampoules improved the crystallinity and orientation for the LaMnPO and LaMnAsO films, but it led to the phase segregation of the LaMnSbO film. Thermopower and optical absorption measurements revealed that all the films are p-type semiconductors with indirect bandgaps from 1.0 to 1.4 eV, which are supported by density functional calculations with the GGA+U approximation. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3093685]